Submarine mine



May 1-5; 1928.

H. B. PRATT SUBMARINE MINE Filed June 28, 1925 5 Sheets-Sheet 0% 2* W 4 a W 4 J 1 4W W E W wQ K E g m ,7 A fl .4 i 6 I z .5 2 w A 1 I 4 M W J w M iiiix? \\\.i 2 4 F A \vl If A w May 15, 1928.

H. B. PRATT VSUIBMARINE MINE Filed June 28, 1926 s Sheets-Sheet 2' May 15, 1928.

H. B. PRATT SUBMARINE MINE Filed June 28, 1926 5 Sheets-Sheet 3 Patented May 15, 1928.

em rge HARTIIEY This invehtiofi r'el'itts to sri'b'ihtrih mines of the kihd in which the aeration tee or miiie erepertiifcl tee water are -lihhc'hed' as a connected uhit afiebecome 'epefated rem each 'oth'erbfy it hydi cistatic predetermified depth less than the depth at -vvfl rich the eif te'rfii'l hjttr'dsta'tic ,p'reseu'fe t v duld be g'r'zttef their the fietatibirhafiiber t'idu'kl s itfely resist, theefdepths beiri'g hefein termed the releztihg tiepth the site 1 depth respectively in suchmifles it has been pr posed when the 'sepaeatien'takes place to l ing out of the mooring ctblein such a manher that the flotation chamber remains at approximately the set depth dlirihg the descefit ofth'e afibhor as described in'United States Patent No. 1,515,195, the pa ifig out of the moei'ngcame bei n'g stopped vwhen the ahchor reziche's the sea bed; It hire flirr elbeefi propesecl in Uhited sta esmen No.1,505,997 te' provide a siiblhtr'iherriine iliary line or cord which is released from the flotation chamber or from the u per end of the mooring cable by'mem fot the depth ing out of the mboring' cable td be st ppea,

the s'itid line er cord being, then no lofiger Supported by the fieta'ti'on" chamber,

According to the preeent ifiventie'rithe hydrostatic device for releasing the flbttticn chamber troih the anchor 13 arrangedto come into oper'ttidfi at at depth 'ubstiritie'l ly I greater then the maximum set depth o'fthe' flotttien chamber, and the retarding devl'ce fer the drum of the Inebr'ifig stitch that during the. subsequent tte scent'p'f the anchor to the sea bed the ffotittion chamber will net rise ab'oyethe set'depth desce'xid if V blefi the Safe depth,- we tlr'dpth settm hydreetavtic device is detthably carried by else been proposed to vary the rztte'of pay of the kind referred to abeve W ith 'aln atlxsetting hydrostatic device to muse the paymeeting repay but the auxiliary wi e tvhen the et dept-h remaeamne 131111 efi'the itiihem in its beer-time htiitidfi; 111 the pfs ere iiir' entio'fi the further jbtlltbfithe dint-i1- h paw seem s e n p ni yiwmdh t fcasifig er the hye dsmtie depth eettiiig' fie- BLYTEPR AT' F eAieeqfij-m-rfiiirregEife A b, Assmeomo #ICKEES LIMITER OF WESTMINSTER;1ENGLAND; A BRITISH COMPANY.

thereldy dich li'c ting Sara deiiitf from the flotation chamber and enziblir'ifi it t6 filtto the sea bed 'togethef-witfi the eeeina detached from the flotation chamber a'the 1 th of ceble appertaiiiirigtethe irereiem' The titled ng Hykirbi e, t ye areas a; s

60 tibly 6f the" kiieti it kiiid havin it deem fluence of the differential hydrostatic pres- .ed; to the anchor v ,tutedibya rod between whichgand a portion ,of-the-spring casing soluble plugiisl arranged." This soluble plugis. provided for sureTis opposedby aspiringof the required strength to enable the releasing member to move and thereby liberate the flotation "chamber' fromthe anchor when thepredetermined releasing depth has been reached. The-lib'en ation of the flotation chamber ma be effected by the well known ball an groove arrangementflin which the balls normally hold, wmemb'ejr connectedto the flotation chamber in engagementtwith j a part connect- Thisy part may be consti- Y the purpose of liberating the flotation chamber fromithe'anchorafter the lapse of a predetermined interval .of time; in the event of the dept-h of sea bei ng less than the aforesaid releasing depth',-and enables the. said rod to-be moved upwards by theupward pull of vthe flotation chamber to bringthe aforesaid yreleasing. member.

I I balls-floppositei the aforesaid groove which ris formed in the releasing member and thereihy efiect therelease of the flotation chamber independently of .the movement of the said In'order that the said invention maybe clearly understood and readily" carried; into i ings, iniwhichze' -c f efi'eet the same will be more fully described qywith reference to E t a wm e y a Fiea i dia rammaticiview shewin i, b A i b jthelseguence of operations of themain parts of the mine from the time of launching to the:momen t when thelflotation chamber is -finally fanchoredat the set depth. 1 a Figures2' and 3 are sectional side elevail 7 I r with 'tl1is invention,,the parts being shewn the position they occupy priorto launch- ;Fig,ure4 1sa section shew ng the-aforesaid fiad m r ve; and

Y' isvthe anchor, C is themooring cable, C is tions' viewed at right angles'to one another shewmg a .mme constructed in accordance Fi gure 5i's ection shewing the aforesaid h st i r sin device t A is the flotation chamber or mine proper,

the mooringcable drum; Dis the hydrostatic 1 setting device, E is the auxiliarygwire appertaining to i this device, 1 F :is [the floodve and G is the hydrostatic releasing e c 1 g i r v Referring to Figures-2 and 3, the flotation Q f hamber or mine proper isshewn by way f example, as of'tlie j well known horned electric, type and may be provided 'withthe gswitchoperating and primer releasing mechk anisin forming. the subject matter of copending fapplication Serial No.]119,0 46,- filed I Jiine 28,'- 1926. ;This flotation c'hamberfis made s iifficieiitly strong to withstand the i hydrostatic pressure at the desired safe depth 7 which may for example be 200 metres. The

tight manner at the upper part of the anchor the interior of which constitutes a buoyancy chamber; and the flotation chamber is held inplace-by 'a turn-buckle arrangement A I interposed between the lower part of theflotation chamber and the hydrostatic releasing'device G; To the lower part of the anchor are pivoted fourlaunching arms B on the'pivbt-s of which rollers arearranged, rollersbeing also carried by .these arms near their upper ends. The said upper ends are provided with hoods b to protectthe horns from damage and the arms are held in, place by pins a which are carried bybrackets on the flotationchamber engage freely in holes in lugs on the saidzarms so thatwhen the flotation chamber becomes liberated from the anchor and rises slowly the said pins are withdrawn from the holes and the arms can then fall outwardly about their pivots.

The mooring cable C passes from' the drumC? over a roller o and a pulleyc and thence to a;spring controlled lever A on the flotation chamber, this lever operating in the manner described in the specification ofmy aforesaid concurrent patent applicationfiie 'ialflio. 119,0i6. The locking pawl Ci for engaging with ratchet teeth o n the drum Cf is normallyheld in the disengaging position by a shearing pin 0 and is placed under/thev influence of a spring 0 serving,when the pin 0 is sheared, to move the :pawl G into engagement with the ratchetv teeth. The said pawl is connected to a wire-,0 which in turn is coupled to tho endof the aforesaid auxiliary wire E a pper V taining to, the hydrostaticdepth setting dcv.ice D; v This device comprises a drum on which the said auxiliary wire is 'wound and Jill! a locking bolt which, when the sct depth is reached, ismoved into a'position to stop the rotation of the drum. The said depth sotting device is preferably constructed in [he manner described inthe specification of my oopending patentapplication Serial No] 119,045, filed June28, 1926. The casing of the "device has a half boss I) whichreceivcs abolt Z} also engaging with a'half boss A on a bracket attached to the flotation chamber A; the saidcasing also has a boss l) through which and a hole in the said bracket ashearing pin r1 passes. The arrangement is such that when a pull is exerted onlhc auxiliary wire E, when the set depth is reached, owing to the stoppage of the rotationof the drum on which this wire is wound. not only is the shearing pin 0? of the pawl C severed .to allow the latter to stop .therotation of the mooring cable drum C, but the shearing pin (Z is severed by the further pull exerted upon the wire owing to the engagement of the pawl with the teeth ofthe drumand the depth setting device D can then fall from the flotation chamber mama to: the previews o'f t he half ,boss'es D A as al iove clesorihei The stated ortl'er paddle brake C (Fi ure 3) which is driven by too'thetl geahiw at an increased. speed from the said clr'uin'. 'TlllS brake 15 ot such cha'racteithat it will irnpose a resistanceto the rotation of the clrumin unwinding the of the anchor hem the releasing depth to the sea bed, theflotation chamber will" not drawn below the safe depth and Will'riot rise the na'iviiinuin set depth which may for example be lOO inetre's, that is to say stich tiines the flotation chamber will always occupy some 13033 61011 between the a rax'iinmn s'etclep'th oi, say, 100 metres and thesafe depth of, say, 2oo metres The btakin'g' torque clue to the'rotation in Water of a paddle brake vatiesas the square of the rotational yelo'city. As the'lnooring c'ahle p ys out from the clrurn', its radius from the axis decreases.

.Le't Revolution speed of the brake; liet T'B ralte torque; y y x y Let P' ull in mooring ca le due to the Brake; h Q -1 Let r Raclius of inooiingeable about the (Irm axis t any stage;

velocity New T yarie'sas R P varies as lies as Rar constantwl'iich is the characteristic of the paddle brake system.

- The resultant force acting on the flotation chamber atany moment is theialgrebraic sum of tli-e' 'following forces: l H

(1)" Thebuoyancy of the flotation Cl-1811? her which is constant and acts upwards,

(2) The pull in the inooringcable clueto the brake which is variable anclacts clown- Warcls; I

(3) The wei mooring cable between the flotationchaxnher and the anchor which acts downwards and increases. t I v The reaction of this resultant force' is the dynamic force clue .to the resistanceiof, the

water correspondingto the velocityot the flotation chamber up or clown. i

The resultantforces actng on the anchor aft anymolnent are the algebraic sum of the following ,(1) The Weigl'it in Water the anchor with the amount of mooring cable still on resistai'ice to the rotation of pgh-t in water of the lehgt h the rum when clecreasjesand easeaewa- V Wards. (2) 'lhepullinthe nio'ori-ng' cable dine te the brake ei-fect, which is Variable and acts upwards.

lhe reac' 'on'tio thisresultant t di'ceis' the ,clynamie' force lclue-to there'sistanc'e' of the V anchor, and with the relative Weights ete. mooring cable su'ch, that during the descent suitably adjusted, it is founcl'that'by using a paclclle'e brake which has the characteristic that P=j constant as explained above,

it is possible'by calculating a suitablefsize i 10f brake to obtain the following isults' (1') The flotation chamber when first re- (2)11; then descends at increasing velocity until the anchor reaches the sea bottoin.

7 With the paddle type of-brake, the characteristics result in the aiiiplit ucle of the Inctionof the flotation chamber beinglessthan tor a type of brake in whiclrthe resistance is not a function of the'squar'e of the rotational "speed. The essential feature" o'fthe brake is that thebrakingforc'e is tuiiction actualsiz'e "of brake required and its speetl oi rotation. relatlve to thefinoormg cable V v diu'in is determined an analysis ofthe between flotation anchor when all their characteristics are motions of'the flotation chamber and the known.

of the square of the rotational Velocity; The

Referring to Figure At which shows the aforesaid flooding valve F in letail t'his ferent effective areas, open to the sea water and is iiorlnally heltli in its clos'e'cllpositio n "againstthe' action of a springF by'a pivot ecl arm I? which retained 'in' the position shewn in Figures 3lanrl" 4 by the Wall ot the launching tube} This arm bears againstf a sliding piece F? between which and a shoul der in the valve F is placed a spring"- piece F is transmitted to the" valve F through thespring' The said sliding piece is forniecl with a hole f to' enable sea Will 1&1 to pass through the central bore of the valve F and act onthe' inner face of the seating portion f y The effective area'olf the portion f is slightly less than the'htfectit-"e area of theportion f so that when the mine unit is launched the spring 1* in openingthe valve F has only to overcome a hydro static pres'sure olep'entlent at'any cle'pth upon the difference in the said effective areas llthe'n the valve isopened the. sea Water enters" the" jbuoyai' cy hamber {of the anchor through holes f in the valve casing and therebygives the mine unit substantial negative buoyancy as aforesaid;-

J 3 Referring to Figure 5, which "shows-indetail the aforesaid hydrostatic releasing dc vicefwhich is interposed between'the anchor and the flotation ychamber, the casing whichis attac hed in a watertight manner oversa holeintheanchor as shewn in. Fig has clamped therein the outer portlons of two flexible diaphragms G1, G the inner. parts of which .are clamped to a sliding sleeve '9; The upper diaphragm G has a larger effective area than the lower. diaphragm G and between them isa space eonta ningair at atmospheric pressure; The sea wateiahas access to the upper surface of the diaphragmGl and to.the lowersurface of the diaphragm G (whenthe aforesaid flooding val've'F is open) through holes. g

g solthat the're is thenla resultant downward hydrostatic pressureatany depth of immersion dependent-upon the difference in the effective areas of'the diaphragms. {The downward movement of the sleeve g is're- 's sted by a spring, G interposed between the sleeve and a partattached to the casing,

the. strength of; this [spring being such that the sleevefg will movedownwards when the ,is reached. The: said downward movement not the sleeve 9 brings a groove 9? w th m- .clined walls opposite balls .9 which are aforesaid releasingdepthlof, say, 18 metres mounted in the wall of the hollow end of a rod G and normall en 'a e .in a roove y a: a a:

gt with inclined walls in an eyeG connected.to the flotation chamber through the aforesaid turn-buckle arrangement A? (Figc nre 2). lVhen the grooveg? comes. opposite f the balls as stated, the upward. pull on the eyeG due to the buoyancy of theflm tationchamber causes the inclined walls of the groove "to press the "balls outwards into. the groove gtandth'e eye G5 is thereby 'liberatedfrom the-"rod Gr? thus enabling the flotation chamber to separate from the an chor. For liberating the fiotationch amber from theanchorwhen th'ejdepth of the sea is i j less than the aforesaidliberating depth, a.

soluble plug G? provided between part of the casing and a collar t on the lower end of therod G When this soluble plughas dissolved afterthe lapse of a suitable interval of, time (water having access thereto through ahol'e 9 the pull on the eye-G and the rodG moves these parts upwards and brings the balls 7" opposite the groove whereuponthe eye is liberated from the i l rod in the mannersdescribed above.

,The sequence of operations in laying a mine in accordance with this invent on-1s shewn diagrammatically; in F igure] 1. in

which the depthof the sea bed is assumed tobe 500 metres, the releasingdepth180 metres and the nanimnmrequired set depth "as will be seen from positions, 3,

100 metres. :The mine unit when in the launching tube has neutral buoyancy as aforesaid and sinks when'the flooding valve inlthe anchor'is opened in the manner above described. Position 1 in Figure 1 represents the mine unit sinking after the flooding valve has been opened- When the mine unit reaches; the predetermined releasing depth 0t 180 metres (position 2) the aforesaid hydrostatic releasing ClGVlCQCOHlQS into operation in the manner hereinbefore described to l berate the flotationchamber A from the anchor B. As the flotation chamber and the anchorseparate the aforesaid pivoted arms "B carried by the anchor B are liberated in thema'nner hcreinbefore described and fall down to a horizontalposition. The anchor then descends and the flotation chamber ascends as'shewn in-the positions 3 and 3 The speed-of ascent oftheflotation chamber is determined by the resultant effect of the force of theflotation chamber buoyancy actmg upwards and the resistance of the aforesaid paddle brake on the mooring cable .drum plusthe weight of the mooring cable paidoutacting downwards. The effect of the brake is such that the motion of the flotation chamberis at first upwards and finally downwards, the total movement be ing well within the limits of the maximum set depth and the safe depth. This is due to'th'e following conditions :.The downward pull on the flotation chamber'due to the mooring cablexisequal to the weight in water of the length of this cable hanging from the flotation chamber between it and-the anchor -plus the pull at the bottom end of this cable 'due to the mooring cable drum brake- 'The virtual downward pull on the flotation chamber due to the auxiliary wire E is equal "to the pull of the brake of the drum appertaining to the hydrostatic depth-setting device D less the weight in water of Wire between the flotation chamber and the anchor. This is because the'tension ofthis wire at the flotation chamber end is always equal to the brake pull on this wire, but the buoyancy of the flotation chamber is increased by the amount of the wire paid out. The remaining active force on the flotation chambe:- is its "buoyancy "acting upwards. The resultanteffect f all these forces on the flotation chamber causes it to first move upwardsand then, as the increased weight of mooring cable makes itselffelt. downwards,

so that its final position when the anchor touches the sea bottom is not very far above 'its position when released from the anchor,

' rea er out and the b ak pu l ac g upward When the anchor lreachestl e sea bed (position {1) the flotation chamber will as above described bc at some depth between the safe de th and the maximun' set depth depending ,on the depth o fthe= a bed. When the anchor-reaches the sea bed t'he flotation chamber proceeds to with a velocity determined 1 by the resultant efie'ct of the upward forceof its buoyancy upwards and the weight in water of the mooring cable Paid but P u e brake pul ti do wards osition hen the flotation chamber reaches its set depth (position 6') the hydrostatic depth setting device Dpn he fietetien c am er op ra es and t ps he P y n ut cf th assay Wire he pward pull o the au i iary" Wir i ran m ttedt the Pau of th ni er na cabl um Whe e it shears'thera cresa dffs a ing Pi and. l ws he sprees-cf thi ra a; push the latter intoj'engagement with "the teeth onthe said .drum and thus locks the latter and stops the paying out of'the'moor ing'cab'le. Ihe pawl is heldin engagement the spring. 'The further shock on the auxiliary wire E at the moment ofpaw'ling effects the release of the hydrostatic device from the flotation chamber. as aforesaid.

The said device and the auxiliary wire then fall freelyto the sea bottom leaving the ing cable.

, flotation chamber moored only by the moor- Vhat I claim and desire to 'secureby Letters Patent ofthe United States is 1. A submarinemine, comprising in combination a flotation chamber, an anchor, a

' hydrostatic device normally connecting said chamber and anchor together and arranged to release said chamber from the anchor when the unit composed iof" these ,parts'has sunk to adepth-substantially-exceeding the maximum set depth at which it is ever'dea sired to anchor the flotationfch amber' beneath the. surface of'the water, a" drum in the anchor, a mooring cable wound on said drum and connected to said chamber, a retarding device for said drum, said device, during the descent of the anchor to the sea bed after separation from the flotation chamber, ensuring that the latter will not rise above the said (ill set depth nor descend below a predetermined lower depth, a depth setting hydrostatic device carried by said flotation chamber, means whereby, when a predetermined depth'has been reached during the ascent of, the flota-i bination ,a flotation chamber, an anchoga V hydrostatic deyice norn ia'lly connecting said chamberand "anchor together and arranged to release sa d chamber fro-in the anchor when the unit composed 'ol' these parts has sunk ton depth substantially exceeding the maximum set depth at which it is ever desired to anchor the flotationchamber beneath the surface of the water, a drum in' the anchor, a mooring cable woundon said drum and connected to sa d chamber, aretarding device'for, said drum, said device,

during the descent of the anchor to the sea rise ab ove' tlie said set depth'nor descend bed after separation fromfthe. flotation chamber ensuring that the "latter will not so aw predete mi d lower d p a depth setting hydrostatic device, a casing ofthe latterldevice, a s'hearing pin connecting said cash g; to the flotationbhamber, a drum w th n said casing, a wire on said drum, a

locking pawl for co-uoperating 'with -th e mooringc'able druinfinthe anchor, and a shearing pin normally holding said pawl in the ino erative position, the latter pi-n being sheare and the pawl brought into its engag ing position when the paying, out off-said I wire is "stopped by the dep'thsetting hydro static device upon a predetermined depth being attainedand the iirst-mentioned pin being thereupon" sheared by the pull "insaid wire causedby thepawl coming into its 'engaging position, the. shearing 'ofthe latter pin separatingv the depth setting hydrostatic device from the flotation 'cha-mben "3. A submarinemine, comprisingin comhydrostatic device normal-1y connecting said 3 chamber and anchor together and arranged to release said chamber from the anchor fwhen the unit composed of these parts has sunk to 'a predetermined depth,"said unit normally (i."e.prior to launching) ,pos'sessingf neutral buoyancy, a buoyancy chamber form'- ing. part of said anchoijand' a floodingvalve controlling a passage leading to the interior bina tion a flotation chamber, ananch'or, a

of said buoyancy chamber, said valve openr ing, after the mine unit has been launched,

to admit sea water to said buoyancy chamber so as to give said unit substantial negative buoyancy. I i a a y 4. A submarine mine, comprising in combination, a flotation chamber, an anchor, a 7 hydrostatic device normally connecting said chamber and anchor together and arranged to release said chamber from the anchor when the unit composed of these parts has sunk to a predetermined depth, said unit normally (i. e. prior to launching) possessing neutralbuoyancy, a buoyancychamber forming part of said anchor, and a flooding valve controlling a passage leading 'to the interior of said buoyancy chamber, said valve having two portions of nearly equal eflective area exposed to the sea water when of theelements claimedin claim 14,019 a e ifieunit is in the sea so thatth n ft f" pressureopens the valve to admitfsea water tosaid buoyancy chamber so. as to give said a unit substantial negative buoyancy, Y a

1 5, In asubmarine minef,' the"combination of the elements claimed in claim 3, ofa member col-acting with the flooding valve to keep the latter closed when the minef is in the launching tube.

6. In a submarine mine, ithefcombination member co-acting with the the fioodingva-lve ing member normally] serving to hold tithe" other two members together, two,.cliaphragms of different effective areas Yc'onnected to said 1 and the pressures on the diaphragms "acting releasing nember, both said diaphragms be; ing exposed to the pressure of the seaywater.

'1 opposition to one another, Q anda' spring acting in opposition to'theamovement o fithe releasing member under increase in the pressure of the'sea water on:v the diaphragms,

' said spring heingof such strength that when; predetermined depth ,of; immers on has,

7 been reached the releasing membenwill aspositions and having a groove which, when sume its-position releasing-the first two members from one another, I r e 8. A submarine mine, comprising in com-v 'bination'afiotation chamher, an anchor,v a member connected to the flotation chamber, a memberconnected tothe anchor, elements carried by one member. andengaging with theother, a relea'sing'memher normally serv 7 being lessthan thedepth at which saidre-I leasing device-avould be brought into action ingto hold saidelements in theirengag ing the releasing member occupies the releasing move totheir disengaging positions, two diaposition, serves to permit {said elementsvto and a spring acting in opposition to the movement of the'releasingrmember under increase in the pressure of the sea wateron the 'diaphragms, said spring I being of such strength that when a. predetermined depth v of'inimersio'nj has been'reached the releasing member \vill".assume its position With the groove therein oppositefsaid elements'so as to; release the first two members from one another. e

9. In a submarine mine, the combination with-the elements claimed in claim 7, of a soluble plug normally actingon themember connectedrto theianchor so a'sto permit said member tolmoye upwards relatively to there leas ng member and vefiect the release of the member connected to theanchor from themember connected, to the flotation chamber I after the 1apse '0f afipredeterinined interval offtime in the event ofv the depth of the sea beingless than the depth at which said releasingde vice would be brought into action by the diaphragmsunder the action ofthe pressure of the sea water. g

10/In a submarine mine,'the combination with the elements claimed in claim 8', of a soluble plug normally acting on the member connected-to the anchorso. as to permit said memberltomove. upwards relatively to the releasing member and effect the release of the member connected to the anchor'from the memher connected to a the (flotation L chamber after the lapse of. a- :predetermined interval oftime' inth ef'event .ofthe depth of the sea by the diaphragms'.undehthe action of the pressure {of the sea waten Y 

